One first solves these equations in the bulk and then implements the \(\delta \) -source via a jump of the first derivatives \(A^{\prime }, B^{\prime }, \chi ^{\prime }\)  at \(r=0\) .
We proceed completely analogously to [1]}, so
that we can keep the presentation short and essentially just describe
the two solutions found there.In fact, in this new approach
we did not find any further relevant solution, either. In appendix  we present a physically less interesting solution we have identified.
